Provided are a lens device capable of preventing a focus shift of an imaging optical system due to heat without reducing a degree of freedom of design, an imaging device comprising the same, and a focus shift correction method of a lens device. A lens device 100 includes an imaging optical system 20 that includes a plurality of lenses, a lens barrel 10 that accommodates the imaging optical system 20, a temperature sensor 30 that is provided outside the lens barrel 10 to detect a temperature of the lens barrel 10, a temperature sensor 50 that is provided outside the lens barrel 10 to detect a temperature of a member 40 of which a temperature characteristic indicating a temperature change with a time change is different from a temperature characteristic of the lens barrel 10, and a focus correction unit 60 that corrects a focus shift of the imaging optical system 20 by controlling a relay lens 25 as a correction lens included in the imaging optical system 20 based on temperature information items respectively detected by the temperature sensor 30 and the temperature sensor 50.
Legal claims defining the scope of protection, as filed with the USPTO.
1. A lens device comprising: an imaging optical system that comprises a plurality of lenses; a lens barrel that accommodates the imaging optical system; a first temperature sensor that is provided outside the lens barrel to detect a temperature of the lens barrel; a second temperature sensor that is provided outside the lens barrel to detect a temperature of a detecting target member provided outside the lens barrel and having a temperature characteristic indicating a temperature change with a time change, close to a temperature characteristic of a specific lens included in the plurality of lenses; a storage medium that stores data obtained by associating a difference value between two temperature information items detected respectively by the first temperature sensor and the second temperature sensor with a relative value of the temperature information of the specific lens in a case where any one of the two temperature information items is used as a reference; and a focus correction unit that calculates a difference value between the two temperature information items detected respectively by the first temperature sensor and the second temperature sensor, estimates the temperature information of the specific lens based on the difference value and the data stored in the storage medium, and corrects a focus shift of the imaging optical system by controlling a correction lens included in the plurality of lenses based on the estimated temperature information.
2. The lens device according to claim 1 , wherein a mass and a specific heat of the detecting target member are approximately equal to a mass and a specific heat of the specific lens.
3. The lens device according to claim 1 , wherein the detecting target member contacts with an outer peripheral surface of the lens barrel, and a contact area of the specific lens and the lens barrel and a contact area of the member and the lens barrel are approximately equal to each other.
4. The lens device according to claim 2 , wherein the detecting target member contacts with an outer peripheral surface of the lens barrel, and a contact area of the specific lens and the lens barrel and a contact area of the member and the lens barrel are approximately equal to each other.
5. The lens device according to claim 1 , wherein the detecting target member is supported by the lens barrel so as to be movable in an optical axis direction of the imaging optical system, and the specific lens is movable in the optical axis direction.
6. The lens device according to claim 2 , wherein the detecting target member is supported by the lens barrel so as to be movable in an optical axis direction of the imaging optical system, and the specific lens is movable in the optical axis direction.
7. The lens device according to claim 5 , wherein, in a state in which a lens group included in the imaging optical system moves in one direction, the detecting target member moves in a direction opposite to the one direction to prevent vibration of a center of gravity of the lens group.
8. The lens device according to claim 6 , wherein, in a state in which a lens group included in the imaging optical system moves in one direction, the detecting target member moves in a direction opposite to the one direction to prevent vibration of a center of gravity of the lens group.
9. An imaging device comprising: the lens device according to claim 1 ; and an imaging element that images a subject through the imaging optical system.
10. A focus shift correction method of a lens device that comprises an imaging optical system comprising a plurality of lenses, and a lens barrel which accommodates the imaging optical system, the method comprising: a temperature difference detection step of detecting a temperature of the lens barrel by a first temperature sensor provided outside the lens barrel, detecting, by a second temperature sensor that is provided outside the lens barrel, a temperature of a detecting target member provided outside the lens barrel and having a temperature characteristic indicating a temperature change with time change close to a temperature characteristic of a specific lens included in the plurality of lenses, and calculating a difference value between two temperature information items respectively detected by the first temperature sensor and the second temperature sensor, and a focus correction step of estimating the temperature information of the specific lens based on data read out from a storage medium which stores data obtained by associating a difference value between two temperature information items detected respectively by the first temperature sensor and the second temperature sensor with a relative value of the temperature information of the specific lens in a case where any one of the two temperature information items is used as a reference and the difference value between two temperature information items calculated in the temperature difference detection step, and controlling a correction lens included in the plurality of lenses based on the estimated temperature information, thereby correcting a focus shift of the imaging optical system.
11. The focus shift correction method of a lens device according to claim 10 , wherein a mass and a specific heat of the detecting target member are approximately equal to a mass and a specific heat of the specific lens.
12. The focus shift correction method of a lens device according to claim 10 , wherein the detecting target member contacts with an outer peripheral surface of the lens barrel, and a contact area of the specific lens and the lens barrel and a contact area of the detecting target member and the lens barrel are approximately equal to each other.
13. The focus shift correction method of a lens device according to claim 11 , wherein the detecting target member contacts with an outer peripheral surface of the lens barrel, and a contact area of the specific lens and the lens barrel and a contact area of the detecting target member and the lens barrel are approximately equal to each other.
14. The focus shift correction method of a lens device according to claim 10 , wherein the detecting target member is supported by the lens barrel so as to be movable in an optical axis direction of the imaging optical system, and the specific lens is movable in the optical axis direction.
15. The focus shift correction method of a lens device according to claim 11 , wherein the detecting target member is supported by the lens barrel so as to be movable in an optical axis direction of the imaging optical system, and the specific lens is movable in the optical axis direction.
16. The focus shift correction method of a lens device according to claim 14 , wherein, in a state in which a lens group included in the imaging optical system moves in one direction, the detecting target member moves in a direction opposite to the one direction to prevent vibration of a center of gravity of the lens group.
17. The focus shift correction method of a lens device according to claim 15 , wherein, in a state in which a lens group included in the imaging optical system moves in one direction, the detecting target member moves in a direction opposite to the one direction to prevent vibration of a center of gravity of the lens group.
Cooperative Patent Classification codes for this invention. Click any code to explore related patents in that topic.
February 26, 2019
September 29, 2020
Browse 5M+ US patents with plain-English claim translations and AI-generated analysis.